Heat exchangers have a hot fluid stream positioned adjacent to a relatively cool fluid stream. The proximity of the fluid steams results in a heat transfer occurring wherein the hot fluid stream loses a portion of its heat to the comparatively cool fluid stream. The heating system of a home could be made more efficient if air entering a forced air furnace was preheated by hot gases in the exhaust stream of the furnace through use of a heat exchanger. There has been a reluctance to equip residential furnaces with heat exchangers, however, due to safety concerns. Electric blowers are required to sustain movement of the hot exhaust gases from the exhaust stream through the heat exchanger and up the chimney. Should the electric blowers fail due to a power failure or mechanical problems, a build up of exhaust gases could result in the asphyxiation of the residents of the home.